Combining Hydrodynamic Modelling and Solar Potential Assessment to Evaluate the Effects of FPV Systems on Mihăilești Reservoir, Romania
Abstract
1. Introduction
2. Materials and Methods
2.1. Study Area
2.2. FPV Configuration
2.3. Water Quality Model
- The Michaelis–Menten Monod equation for nutrient limitation , , ;
- The Steele formulation for the limitation due to light intensity ;
- An exponential relation for temperature .
- I represents the light intensity, , ϑT, and kspP, kspP, and β are explained in Table 3. The loss processes due to respiration are considered as both the endogenous component (re) and as photosynthesis (rf): with and and . The excretion and mortality terms are considered by and .
3. Results and Discussion
4. Conclusions
- The data obtained from the calibrated model are similar to the measured ones, observing that the values of correlations for all the investigated variables are greater than 0.9.
- Upon analysing the deviations in the quality indicator values across the four scenarios relative to the hypothesis of the lake not being covered by FPV panels, it is obvious that the reservoir water temperature and the phytoplankton biomass values diminish as the coverage degree grows, whereas the nutrient concentration values indicate a slight increase. A drop in the temperature values is predicted (between almost 2% and 10%, depending on the scenario), as well as a diminishment of the concentration of phytoplankton, ranging from 13% up to 50%. In terms of nutrients, an increase in their concentrations is expected, obviously in connection with the decrease in the phytoplankton concentration. Thus, the nitrogen and phosphorus concentrations will increase by between 4% and 15%.
- The proposed solution would generate between almost 80 and 340 GWh/year.
- Depending on the analysed scenario, covering the reservoir’s surface with FPV panels will reduce evaporative water losses from the reservoir by 70 to 380 Mm3/year.
- The placement of FPV panels on the surface of the Mihăilești HPP Reservoir will contribute to GHG reductions of between 15 and 66 tCO2e/year.
Author Contributions
Funding
Data Availability Statement
Acknowledgments
Conflicts of Interest
Abbreviations
FPV | floating photovoltaic |
GHG | greenhouse gas |
HPP | hydropower plant |
NARW | National Administration “Romanian Waters” |
DO | dissolved oxygen (mg/L) |
TN | total nitrogen (mg/m3) |
TP | total phosphorus (mg/m3) |
T | temperature (°C) |
A | phytoplanktonic biomass (mg/m3) |
K(z) | vertical diffusion coefficient (m2/s) |
w | vertical velocity (m/s) |
S | cross-sectional area (m2) |
RS | source term due to surface-atmosphere exchanges (W/m2) |
ρ | water density (kg/m3) |
Cp | specific heat (J/kg°C) |
growth(T,TP,TN) | growth term for phytoplankton |
loss(T) | losses term by respiration and mortality for phytoplankton |
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Parameter | Value |
---|---|
Longitude | 44.32979 DD |
Latitude | 25.905075 DD |
Normal operating level | 86.5 MASL |
Maximum dam height | 22 m |
Reservoir mean height | 13 m |
Reservoir surface | 1030 ha |
Reservoir length | 8 km |
Length of frontal and lateral dikes | 13.49 km |
Maximum reservoir width | 3 km |
Total reservoir volume | 99 × 106 m3 |
Attenuation reservoir volume | 46.3 × 106 m3 |
Dam length | 48 m |
Net head | 18 m |
Installed flow in the HPP | 58 m3/s |
Installed capacity of the HPP | 8 MW |
Energy generation of the HPP | 24 GWh/year |
Scenario | FPV Coverage Rate (%) | FPV Surface (ha) |
---|---|---|
No. 1 | 5 | 48 |
No. 2 | 10 | 96 |
No. 3 | 15 | 144 |
No. 4 | 20 | 192 |
Symbol | Description | Range [27] | Assigned Value |
---|---|---|---|
growthmax | Maximum phytoplankton growth rate | 0.5 to 20 | 0.75 day−1 |
ϑT | Non-dimensional temperature multiplier | 0.02 to 1.06 | 0.0682 |
ksp P | Half saturation constant for phytoplankton P uptake | 0 to 10 | 5 mg∙m−3 |
ksp N | Half saturation constant for phytoplankton N uptake | 0 to 120 | 15 mg∙m−3 |
β | Light intensity coefficient | 10−3 to 10−2 | 0.002 |
coefre | Respiration coefficient | 0 to 0.2 | 0.0175 |
kr | Growth rate for algal biomass | 0 to 0.3 | 0.025 |
coefexret | Excretion coefficient | 0 to 0.25 | 0.03 |
coefmort | Mortality coefficient | 0 to 0.2 | 0.2 |
ε | Efficiency factor | 0 to 0.8 | 0.6 |
apa | Phosphorus/chlorophyll ratio in phytoplankton | 1 | 1 mg P∙mg Chla−1 |
cza | Predation coefficient of algae by zooplankton | 0.0025 | 0.0025 |
ana | Nitrogen/chlorophyll ratio in phytoplankton | 1 | 1 mg N∙mg Chla−1 |
Scenario | Installed Capacity (MWp) | Power Density (MW/km2) | Annual Energy (GWh/year) |
---|---|---|---|
No. 1 | 70 | 145.83 | 79.05 |
No. 2 | 150 | 156.25 | 169.40 |
No. 3 | 250 | 173.611 | 282.30 |
No. 4 | 300 | 156.25 | 338.80 |
Scenario | Direct Water Saving | Increase in Hydro Power | Indirect Water Saving | Energy Ratio | |
---|---|---|---|---|---|
(106 m3/Year) | (MWh) | % | (106 m3/Year) | ||
No. 1 | 0.42 | 14.93 | 0.62 | 1.33 | 3.32 |
No. 2 | 0.84 | 29.86 | 1.252 | 2.87 | 7.10 |
No. 3 | 1.26 | 44.79 | 1.878 | 4.87 | 11.84 |
No. 4 | 1.69 | 59.72 | 2.504 | 5.74 | 14.21 |
FPV Coverage Rate | 0% | 5% | 10% | 15% | 20% | ||||
---|---|---|---|---|---|---|---|---|---|
Value | Value | % | Value | % | Value | % | Value | % | |
T (°C) | 18.11 | 17.72 | 0.62 | 17.29 | −4.57 | 16.8 | −7.25 | 16.25 | −10.27 |
TN (mg/m3) | 982.5 | 1022 | 1.25 | 1061.38 | 8.03 | 1100 | 11.96 | 1137.51 | 15.78 |
TP (mg/m3) | 32.68 | 34 | 1.88 | 35.34 | 8.12 | 36.64 | 12.11 | 37.9 | 15.96 |
A (mg/m3) | 7.22 | 6.28 | 2.50 | 5.35 | −25.95 | 4.44 | −38.59 | 3.56 | −50.79 |
Scenario | Total Water Saving (106 m3/year) | GHG Emission Reduction Associated with FPV System (tCO2e/year) |
---|---|---|
No. 1 | 1.75 | 15,415 |
No. 2 | 3.71 | 33,033 |
No. 3 | 6.04 | 55,049 |
No. 4 | 7.43 | 66,066 |
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Dumitran, G.E.; Preda, E.C.; Vuta, L.I.; Popa, B.; Ispas, R.E. Combining Hydrodynamic Modelling and Solar Potential Assessment to Evaluate the Effects of FPV Systems on Mihăilești Reservoir, Romania. Hydrology 2025, 12, 157. https://doi.org/10.3390/hydrology12060157
Dumitran GE, Preda EC, Vuta LI, Popa B, Ispas RE. Combining Hydrodynamic Modelling and Solar Potential Assessment to Evaluate the Effects of FPV Systems on Mihăilești Reservoir, Romania. Hydrology. 2025; 12(6):157. https://doi.org/10.3390/hydrology12060157
Chicago/Turabian StyleDumitran, Gabriela Elena, Elena Catalina Preda, Liana Ioana Vuta, Bogdan Popa, and Raluca Elena Ispas. 2025. "Combining Hydrodynamic Modelling and Solar Potential Assessment to Evaluate the Effects of FPV Systems on Mihăilești Reservoir, Romania" Hydrology 12, no. 6: 157. https://doi.org/10.3390/hydrology12060157
APA StyleDumitran, G. E., Preda, E. C., Vuta, L. I., Popa, B., & Ispas, R. E. (2025). Combining Hydrodynamic Modelling and Solar Potential Assessment to Evaluate the Effects of FPV Systems on Mihăilești Reservoir, Romania. Hydrology, 12(6), 157. https://doi.org/10.3390/hydrology12060157